Artificial Hip Joint Manufactured For Precision Fit
Artificial hip joints must be manufactured with high precision, especially in the area where the hip stem and the ball joint connect. CERATIZIT has developed an economical production solution for precise interface between hip stem and ball joint.
If a hip joint is affecting quality of life by restricting movement and causing chronic pain, and if conservative treatment methods are no longer helping, the only option is to have an artificial replacement joint implanted – over 200,000 such operations are performed in Germany-alone each year. Those who take this route are hoping for long-lasting improvements. In order to make this hope a reality, as well as a good surgeon and first-rate care, the highest quality ‘spare parts’ are needed.
Prosthetics like this usually consist of a hip stem with ball joint, a hip socket and an intermediate piece to ensure movement is as smooth as possible. Particular attention must be paid to the connection between the hip stem and the ball joint. For the conical surfaces to fit together perfectly, they need to be produced with the highest precision and surface quality. Therefore, the tools used play a crucial role when manufacturing these components.
“An artificial hip joint consists of difficult-to-machine materials, which not only need to be machined within the narrowest tolerances but also as economically as possible. Ultimately, an artificial hip replacement should be affordable for as many people as possible. We work with great dedication to find suitable tool solutions for these tasks,” explained Dirk Martin, Application Manager Medical at CERATIZIT and member of Team Cutting Tools.
Meeting Machining Requirements
CERATIZIT is a full-range provider in the machining sector that has a wide range of standard and specially-made tools as well as in-depth machining expertise at its disposal. “With our huge product range and the expertise of our application specialists, we are extremely well equipped for tasks like machining the area where the hip stem and joint ball connect,” stresses Martin. “With our range of tools, we can test all manner of approaches to ultimately find the optimal solution.”
In the case of the artificial hip joint, the customer has particularly demanding and varied requirements. For the hip stem, made from high-strength titanium alloy Ti6Al4V, an angle tolerance of just +/-5‘ must be achieved in the conical connection area. Other tolerances are 3 µm for straightness, 8 µm for roundness and 60 µm for the diameter. It is also important that the specified contact ratio for the cone is achieved and a precisely defined groove profile produced.
The ball joint is made from a cobalt-based alloy (Co-Cr-Mo). Its conical hole must have the same shape, angle and dimension tolerances, as well as the specified contact ratio. However, there must be no marks, ridges or grooves made during machining. Martin mentions another crucial factor: “We need a production solution that is suitable for mass production. This means the machining must be process-secure and require as little monitoring as possible.”
Flexible u-Axis and Special Conical Reamer
To produce the conical outside profile, CERATIZIT’s application specialists opted for pre-machining with a solid carbide conical milling cutter. The subsequent roughing and finishing are then completed using a CERATIZIT u-axis system.
“This is an interchangeable, freely programmable NC axis for machining centres, which can be used to machine contours or for turning.” explains Martin.
“Attachment tools and indexable inserts can be used to create contours in holes and external machining work. This usually means that production times can be reduced considerably, while providing optimal surface quality and higher shape accuracy than usual,” he continued.
This means the desired groove structure can be produced on the stem cone even on a machining centre. This has the benefit that all machining processes can be done on a single machine. Using the conventional process, a lathe and a milling machine would be required, which means additional clamping, aligning, time and money.
To make the conical hole in the ball joint, CERATIZIT’s solution involved the following steps being carried out on a lathe: First, the part is faced to provide a flat surface for the subsequent special solid carbide 180 deg drill with four cutting edges. This is then used to make a hole with a flat bottom. After this an EcoCut Classic drill and turning tool is used to produce the cone with close-contour boring, while a special solid carbide conical reamer ensures the ideal contact pattern and perfect surface quality and tolerance is achieved. The regrinding capability also saves the user further production costs.
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Shifting Gears: Addressing New Requirements In EV Manufacturing
Andy Kuklinski of Ceratizit talks about the electric vehicle trend in the automotive industry, how it has changed the machining landscape, and the new requirements being faced by manufacturers. Article by Stephen Las Marias.
Andy Kuklinski
The Ceratizit Group develops and produces highly specialised cutting tools, indexable inserts, rods made from hard materials, and wear parts. Active in more than 80 countries worldwide, the Group has more than 8,000 employees and over 30 production sites. Its innovative hard material solutions are used in various sectors, including mechanical engineering and toolmaking, wood and stone working, in the automotive and aerospace industries, and in the oil, gas and medical industries.
In an interview with Asia Pacific Metalworking Equipment News, Andy Kuklinski, Head of Segment Automotive/Team Cutting Tools at Ceratizit, talks about the electric vehicle trend in the automotive industry, how it has changed the machining landscape, and the new requirements being faced by manufacturers.
HOW HAVE THE REQUIREMENTS IN ELECTRIC VEHICLES (EVs) CHANGED THE AUTOMOTIVE MANUFACTURING LANDSCAPE?
Andy Kuklinski (AK): One of the changes is that even more components will be made of aluminium. This will affect and change the manufacturing and supplier strategy. A typical example are cylinder heads and cylinder blocks. While these parts used to be manufactured mainly by the OEMs themselves, the focus is now moving to Tier 1 and even Tier 2 suppliers for the machining of the electric engine casing. We are increasingly seeing former aluminium foundries now responding and manufacturing the finished machined part in the same production facility. So, the landscape, especially the supply chain landscape, will definitely look different towards EV manufacturing.
WHAT KEY CHALLENGES HAVE YOU BEEN HEARING FROM YOUR AUTOMOTIVE CUSTOMERS WHO ARE TRANSITIONING TO EV?
AK: We are in constant exchange with our customers and hear again and again how challenging it is to react to the enormous and rapid changes in automotive components. In particular, the R&D and production planning departments are under great time pressure to meet the massively increasing demand for EVs. By supporting them quickly with the right machining concepts, we can mitigate at least some of this pressure.
HOW DO THESE CHALLENGES DIFFER FROM THE TRADITIONAL INTERNAL COMBUSTION ENGINE VEHICLES?
AK: For one thing, the time pressure was much less with the combustion vehicles, since it was not necessary to renew large parts of the portfolio in a short period of time. The product cycles were very finely tuned. For another, the parts that are being created now, especially in the powertrain area, are completely different from the parts that car companies produced in the past—many things are still new and simply bring new challenges. Previous combustion engines were always developed in a similar way and always had the same contours and materials that people knew how to process. In many respects, it was a constant process of optimisation.
HOW ARE THESE CHALLENGES IMPACTING YOUR TECHNOLOGY/PRODUCT DEVELOPMENT STRATEGIES?
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CERATIZIT Hosts eCarbide Online Seminar Week
The CERATIZIT Group’s Hard Material Solutions division will host the eCarbide online seminar week from 15 to 19 March. Covering a wide range of topics from carbide basics to expert knowledge, the series aims to give participants the edge they need in order to prevail.
Cemented carbide stands unrivalled in the fields of tool manufacturing, metal forming and many other industrial sectors. In an upcoming online seminar series, the experts of the CERATIZIT Group’s Hard Material Solutions will share their extensive knowledge free of charge, giving participants the competitive edge that is needed to prevail in today’s markets. The seminars are specifically designed to provide participants with first-hand knowledge and insider perspectives on applications, latest industry trends and the advantages of cemented carbide as compared with other hard materials.
In addition to the wealth of market-critical information, Q&A sessions after each seminar will give participants the opportunity to explore the topics even further. This free online seminar series will take place from 15 to 19 March 2021 in a remote online setting that offers participants an environment both convenient and safe.
Additional information on the eCarbide series and the content of the individual seminars, along with the registration links, is available at https://www.ceratizit.com/int/en/company/trade-shows/online-seminars.html.
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CERATIZIT Wins Innovation Award For The Additive Manufacturing Of Carbide Parts
The CERATIZIT Group has won the 2020 Innovation Award of the FEDIL business federation in the ‘Process’ category for the development of a new process for the additive manufacturing of tungsten carbide-cobalt. Thus, the Luxembourg hard materials specialist has established itself as a pioneer in the additive manufacturing of cemented carbide components.
The additive manufacturing of components made of plastic, steel and other materials has continued to grow in importance over the last few years. However, in the case of cemented carbide, there had not been a reliable process so far that achieved the same standard of quality as the manufacturing processes that had been established and optimised over decades. With its newly developed process, CERATIZIT not only achieves the customary quality of products manufactured by pressing and machining but can also respond better to customer requirements, as Head of R&D Dr. Ralph Useldinger explained:
“Additive manufacturing of carbide products provides us with more flexibility in terms of implementing customer requirements and opens new design possibilities, which we can use to offer our customers highly optimised, individual solutions in minimum time.” This also includes active support in optimising product design, as Useldinger emphasised.
Faster delivery at lower costs
One of the main advantages of the additive manufacturing of cemented carbide is the time and cost savings during the critical ramp-up of products in small batches and of high complexity such as the manufacturing of prototypes. By producing the geometry directly from the design software, 3D printing allows for the fast planning and implementation of projects, without the use of production-intensive shapes and dies as well as expensive, diamond-tipped tools which are needed for the machining of carbide parts. This undoubtedly saves a lot of valuable time and money, particularly in the development of prototypes.
More freedom of design
The second big benefit of additive manufacturing is the wider range of possible shapes due to the direct production of free-form contours which go way beyond the limits of traditional manufacturing processes. Thanks to the new process, geometries can now be manufactured that were previously considered unfeasible. These include, for instance, structures that have undercuts or areas inaccessible to cutting tools such as cavities and channels inside the finished body which cannot be accessed from outside at a later stage. This innovation enables a higher degree of component complexity as well as a deeper level of integration while at the same time reducing the number of assemblies and individual components.
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